This week was rocky for the stock market, with fear of what's to come with coronavirus stymieing the market. 

Friday, the Dow Jones Industrial Average dropped by more than 1,000 points at some points during trading, the third time this week that happened.

But Donald Dutkowsky, economics professor at the Maxwell School, says don't think in terms of points but in percentage. 

" 'The Dow's off 1,000 points, oh my goodness, that's horrible.' But the Dow's [near] 30,000 points, so that's a 3% drop," said Dutkowsky. 

A 3% drop is not good, but not awful, says Dutkowsky. He says the worst single-day drop was the "Black Monday" crash of October 1987, a 22% drop in one day.

This is what is called a "correction," which usually comes after a relatively long good run. 

"For a correction in the stock market is when it's between 10% to 20% lower than its peak," said Dutkowsky. 

The market is down about 13% from its peak. 

"One of the ways I explain it is like the basketball team playing an opponent and they get a run of 10 or 12 points. OK, time out, time out. We're still ahead, but let's settle down," said Dutkowsky. 

We're not yet at a bear market when the market's 20% below its peak. During the 2008 financial crisis, the stock market for the year lost 36%. 

"But every year after that, with the exception of 2018, has been positive," said Dutkowsky.

Dutkowsky has some advice for you. 

"I would advise investors to take a deep breath. If you're in it for the long-term for like your pension, take a deep breath and stay the course," said Dutkowsky.